Bohrium

Bohrium,  107Bh
General properties
Pronunciationm/ (About this soundlisten) (BOHR-ee-əm)
Mass number270 (most stable isotope) (unconfirmed: 278)
Bohrium in the periodic table
HydrogenHelium
LithiumBerylliumBoronCarbonNitrogenOxygenFluorineNeon
SodiumMagnesiumAluminiumSiliconPhosphorusSulfurChlorineArgon
PotassiumCalciumScandiumTitaniumVanadiumChromiumManganeseIronCobaltNickelCopperZincGalliumGermaniumArsenicSeleniumBromineKrypton
RubidiumStrontiumYttriumZirconiumNiobiumMolybdenumTechnetiumRutheniumRhodiumPalladiumSilverCadmiumIndiumTinAntimonyTelluriumIodineXenon
CaesiumBariumLanthanumCeriumPraseodymiumNeodymiumPromethiumSamariumEuropiumGadoliniumTerbiumDysprosiumHolmiumErbiumThuliumYtterbiumLutetiumHafniumTantalumTungstenRheniumOsmiumIridiumPlatinumGoldMercury (element)ThalliumLeadBismuthPoloniumAstatineRadon
FranciumRadiumActiniumThoriumProtactiniumUraniumNeptuniumPlutoniumAmericiumCuriumBerkeliumCaliforniumEinsteiniumFermiumMendeleviumNobeliumLawrenciumRutherfordiumDubniumSeaborgiumBohriumHassiumMeitneriumDarmstadtiumRoentgeniumCoperniciumNihoniumFleroviumMoscoviumLivermoriumTennessineOganesson
Re

Bh

(Uhu)
seaborgiumbohriumhassium
Atomic number (Z)107
Groupgroup 7
Periodperiod 7
Blockd-block
Element category  transition metal
Electron configuration[Rn] 5f14 6d5 7s2[1][2]
Electrons per shell
2, 8, 18, 32, 32, 13, 2
Physical properties
Phase at STPsolid (predicted)[3]
Density (near r.t.)37.1 g/cm3 (predicted)[2][4]
Atomic properties
Oxidation states(+3), (+4), (+5), +7[2][4] (parenthesized: prediction)
Ionization energies
  • 1st: 740 kJ/mol
  • 2nd: 1690 kJ/mol
  • 3rd: 2570 kJ/mol
  • (more) (all but first estimated)[2]
Atomic radiusempirical: 128 pm (predicted)[2]
Covalent radius141 pm (estimated)[5]
Other properties
Crystal structurehexagonal close-packed (hcp)
Hexagonal close-packed crystal structure for bohrium

(predicted)[3]
CAS Number54037-14-8
History
Namingafter Niels Bohr
DiscoveryGesellschaft für Schwerionenforschung (1981)
Main isotopes of bohrium
Iso­topeAbun­danceHalf-life (t1/2)Decay modePro­duct
278Bh[6]syn11.5 min?SF
274Bhsyn44 s[7]α270Db
272Bhsyn11 sα268Db
271Bhsyn1.5 s[8]α267Db
270Bhsyn1 minα266Db
267Bhsyn17 sα263Db
| references

Bohrium is a synthetic chemical element with symbol Bh and atomic number 107. It is named after Danish physicist Niels Bohr. As a synthetic element, it can be created in a laboratory but is not found in nature. It is radioactive: its most stable known isotope, 270Bh, has a half-life of approximately 61 seconds, though the unconfirmed 278Bh may have a longer half-life of about 690 seconds.

In the periodic table of the elements, it is a d-block transactinide element. It is a member of the 7th period and belongs to the group 7 elements as the fifth member of the 6d series of transition metals. Chemistry experiments have confirmed that bohrium behaves as the heavier homologue to rhenium in group 7. The chemical properties of bohrium are characterized only partly, but they compare well with the chemistry of the other group 7 elements.

History

Element 107 was originally proposed to be named after Niels Bohr, a Danish nuclear physicist, with the name nielsbohrium (Ns). This name was later changed by IUPAC to bohrium (Bh).

Discovery

Two groups claimed discovery of the element. Evidence of bohrium was first reported in 1976 by a Soviet research team led by Yuri Oganessian, in which targets of bismuth-209 and lead-208 were bombarded with accelerated nuclei of chromium-54 and manganese-55 respectively.[9] Two activities, one with a half-life of one to two milliseconds, and the other with an approximately five-second half-life, were seen. Since the ratio of the intensities of these two activities was constant throughout the experiment, it was proposed that the first was from the isotope bohrium-261 and that the second was from its daughter dubnium-257. Later, the dubnium isotope was corrected to dubnium-258, which indeed has a five-second half-life (dubnium-257 has a one-second half-life); however, the half-life observed for its parent is much shorter than the half-lives later observed in the definitive discovery of bohrium at Darmstadt in 1981. The IUPAC/IUPAP Transfermium Working Group (TWG) concluded that while dubnium-258 was probably seen in this experiment, the evidence for the production of its parent bohrium-262 was not convincing enough.[10]

In 1981, a German research team led by Peter Armbruster and Gottfried Münzenberg at the GSI Helmholtz Centre for Heavy Ion Research (GSI Helmholtzzentrum für Schwerionenforschung) in Darmstadt bombarded a target of bismuth-209 with accelerated nuclei of chromium-54 to produce 5 atoms of the isotope bohrium-262:[11]

+ +

This discovery was further substantiated by their detailed measurements of the alpha decay chain of the produced bohrium atoms to previously known isotopes of fermium and californium. The IUPAC/IUPAP Transfermium Working Group (TWG) recognised the GSI collaboration as official discoverers in their 1992 report.[10]

Proposed names

Naming ceremony conducted at the GSI on 7 September 1992 for the namings of elements 107, 108, and 109 as nielsbohrium, hassium, and meitnerium

In September 1992, the German group suggested the name nielsbohrium with symbol Ns to honor the Danish physicist Niels Bohr. The Soviet scientists at the Joint Institute for Nuclear Research in Dubna, Russia had suggested this name be given to element 105 (which was finally called dubnium) and the German team wished to recognise both Bohr and the fact that the Dubna team had been the first to propose the cold fusion reaction to solve the controversial problem of the naming of element 105. The Dubna team agreed with the German group's naming proposal for element 107.[12]

There was an element naming controversy as to what the elements from 104 to 106 were to be called; the IUPAC adopted unnilseptium (symbol Uns) as a temporary, systematic element name for this element.[13] In 1994 a committee of IUPAC recommended that element 107 be named bohrium, not nielsbohrium, since there was no precedence for using a scientist's complete name in the naming of an element.[13][14] This was opposed by the discoverers as there was some concern that the name might be confused with boron and in particular the distinguishing of the names of their respective oxyanions, bohrate and borate. The matter was handed to the Danish branch of IUPAC which, despite this, voted in favour of the name bohrium, and thus the name bohrium for element 107 was recognized internationally in 1997;[13] the names of the respective oxyanions of boron and bohrium remain unchanged despite their homophony.[15]

Other Languages
Afrikaans: Bohrium
አማርኛ: ቦህሪየም
العربية: بوريوم
aragonés: Bohrio
armãneashti: Bohriu
asturianu: Bohriu
azərbaycanca: Borium
Bân-lâm-gú: Bohrium
беларуская: Борый
беларуская (тарашкевіца)‎: Борыюм
भोजपुरी: बोरियम (तत्व)
български: Борий
བོད་ཡིག: བོཧ་རིམ།
bosanski: Borij
brezhoneg: Bohriom
català: Bohri
Чӑвашла: Бори
Cebuano: Bohryo
čeština: Bohrium
corsu: Bohriu
Cymraeg: Bohriwm
dansk: Bohrium
Deutsch: Bohrium
eesti: Bohrium
Ελληνικά: Μπόριο
español: Bohrio
Esperanto: Boriumo
euskara: Bohrio
فارسی: بوهریم
Fiji Hindi: Bohrium
français: Bohrium
furlan: Bohri
Gaeilge: Bóiriam
Gaelg: Bohrium
Gàidhlig: Bohrium
galego: Bohrio
ગુજરાતી: બોહ્રીયમ
客家語/Hak-kâ-ngî: Bohrium
хальмг: Борум
한국어: 보륨
հայերեն: Բորիում
हिन्दी: बोरियम
hrvatski: Borij
Ido: Boriumo
Bahasa Indonesia: Bohrium
interlingua: Bohrium
italiano: Bohrio
עברית: בוהריום
Basa Jawa: Bohrium
Kabɩyɛ: Bɔrɩyɔm
қазақша: Борий
Kiswahili: Bohri
коми: Борий
Kreyòl ayisyen: Bòryòm
kurdî: Bohriyûm
Кыргызча: Борий
кырык мары: Борий
Latina: Bohrium
latviešu: Borijs
Lëtzebuergesch: Bohrium
lietuvių: Boris
Ligure: Bohrio
Limburgs: Bohrium
la .lojban.: jinmrbori
magyar: Borium
македонски: Бориум
മലയാളം: ബോറിയം
मराठी: बोहरियम
Bahasa Melayu: Bohrium
Mìng-dĕ̤ng-ngṳ̄: Bohrium
монгол: Бори
Nederlands: Bohrium
नेपाली: बोरियम
नेपाल भाषा: बोरियम
日本語: ボーリウム
Nordfriisk: Bohrium
norsk: Bohrium
norsk nynorsk: Bohrium
ଓଡ଼ିଆ: ବୋଃରିଅମ
oʻzbekcha/ўзбекча: Boriy (unsur)
पालि: बोरियम
پنجابی: بوہریم
português: Bóhrio
română: Bohriu
Runa Simi: Bohriyu
русский: Борий
संस्कृतम्: बोरियम
Scots: Bohrium
Seeltersk: Bohrium
shqip: Bohriumi
sicilianu: Bohriu
Simple English: Bohrium
slovenčina: Bohrium
slovenščina: Borij
Soomaaliga: Bohriyaam
کوردی: بۆریۆم
српски / srpski: Боријум
srpskohrvatski / српскохрватски: Borijum
suomi: Bohrium
svenska: Bohrium
Tagalog: Boryo
தமிழ்: போரியம்
татарча/tatarça: Борий
తెలుగు: బోరియం
Türkçe: Bohriyum
українська: Борій
اردو: بورئیم
ئۇيغۇرچە / Uyghurche: بوھرىي
vepsän kel’: Borii
Tiếng Việt: Bohri
文言: 𨨏
Winaray: Bohryo
Yorùbá: Bohriomu
粵語: 𨨏
中文: 𨨏